Unadjusted and adjusted hierarchical regression model-Percentage removal.

Confidence Interval in parentheses; Note: p value for all the parameters was less than 0.01. *p<0.05, n = 30. A: Main effect, B: Adjusting for concentration and individual elements, C: Adjusting for concentration, interaction between the treatment and the concentration, and individual elements. Note: Each model includes the coefficient and their confidence interval in bracket.